1. Field of the Invention
The present invention relates to mobile communications networks and, more particularly to ad hoc network route creation protocols and route maintenance protocols using a modified Domain Name Service.
2. Description of the Prior Art
Cellular service providers presently offer limited mobile data networking services even though their cellular networks are particularly designed to carry voice communications more than data-rich transmissions. The amount of RF spectrum assigned to a voice channel is carefully sized to carry voice, but this sizing can be a severe limitation when carrying data. The networking technology used to carry voice is based on “virtual private circuits.” That is, once a connection is established and regardless of how infrequently the channel is used, charges are based on the amount of time the circuit exists. In contrast, data networks employ a technology called “packet switching” that allows for a more equitable rate structure based on network usage (i.e., the number of data packets delivered). Another benefit of packet switching is that the hardware is comparatively less expensive and easier to maintain.
The Internet is comprised substantially of a vast collection of interconnected wired networks. Routers connect networks to each other. Each router maintains a routing table that identifies the networks and routers reachable from that router. Routing tables work well in situations where the connectivity between nodes does not change rapidly. Every computer connected to the Internet has a unique Internet protocol (IP) address that encodes necessary information usable for routing packets to that node. A node cannot be disconnected from one network and connected to a different network without changing the IP address of the node. It is generally understood that the performance of conventional techniques used for routing packets through the Internet degrades in larger networks with rapidly changing configurations such as a metropolitan area mobile network.
Current cellular mobile networks are not entirely mobile, that is, while the terminal (customer) nodes are mobile, the rest of the network is stationary. In contrast, ad hoc networks are mobile networks in which intermediate nodes (as well as terminal nodes) can move while they relay data. By combining the features of the cellular mobile network with an ad hoc network into a “hybrid mobile network,” cellular service providers realize significant benefits. For example, presently the coverage area of conventional cellular mobile networks only extends as far as the area covered by its mobile base stations. If a new area is to be covered by the mobile network, additional mobile base stations must be erected and strategically placed. In a hybrid mobile network, packets of data hop from mobile node to mobile node until the packets reach their destinations or a mobile base station. Thus, the coverage area of the hybrid mobile network extends much further than that of a conventional cellular mobile network. In a hybrid mobile network, the area has overlapping coverage, resulting in a more resilient and robust network. Suppose a mobile base station is experiencing hardware problems; network traffic through that base station is rerouted to neighboring mobile base stations by “hopping” through mobile nodes in the vicinity. In addition, when a mobile base station is deluged with communication requests, some of the congestion is offloaded to neighboring mobile base stations by hopping from mobile node to mobile node. Another advantage is that while still providing broad coverage, cellular service providers have an option to deploy new services to a select subset of mobile base stations. A hybrid mobile network establishes a growth path to a unified wireless, IP-based, packet-switching network for all data, including voice.
A proactive-reactive hybrid routing protocol is disclosed for use in ad-hoc networks in U.S. Pat. No. 6,304,556, issued Oct. 16, 2001 to Z. J. Haas, entitled “Routing and Mobility Management Protocols for Ad-Hoc Networks,” assigned to Cornell Research Foundation, Inc. The mobility management protocol has some of the network nodes assuming the mobility management function by forming a virtual network embedded within the actual ad-hoc network with each participating management node knowing and communicating the location of all nodes within its zone. Other mobility management techniques are discussed in U.S. Pat. No. 6,160,804, issued Dec. 12, 2000 to W. Ahmed, et al., entitled “Mobility Management for a Multimedia Mobile Network,” assigned to Lucent Technologies, Inc.